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Image: Kater pendulum use

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Description: Drawing of the use of a Kater's pendulum, a reversible freeswinging pendulum invented in 1817 by British captain Henry Kater as a gravimeter instrument to measure the local acceleration of gravity. The image shows Kater's original pendulum, and is probably from Kater's original 1818 paper. The pendulum had two opposing pivots near either end of the rod, consisting of short knife blades, so it could be hung from either end, with the knife blades resting on agate plates. As shown, the pendulum was swung in front of a precision pendulum clock that had been adjusted to keep correct time by the passage of stars overhead. The precise times when the two pendulums swung in synchronism were determined by looking through the sight on the left, to eliminate parallax error. The adjustment weight on the rod was adjusted until the pendulum had the same period of swing when hung from either pivot. From this period and the distance between the pivots the strength of gravity could be calculated precisely. Alterations to image: removed frame, converted to 32 greyscale PNG.
Title: Kater pendulum use
Credit: Downloaded 2009-01-30 from John Cox (1904) Mechanics, Cambridge Univ. Press, London, p.308, fig.147 on Google Books. The same picture in Victor F. Lenzen, Robert P. Multauf (1964) 'Paper 44: Development of gravity pendulums in the 19th century', Smithsonian Institution Bulletin, 1964, Smithsonian Institution press, Washington, p.316, fig.12 credited in text to Collection de Mémoires Relatifs a la Physique, publiés par la Société Française de Physique, Vol.4, Mémoires sur le pedule, précédés d'une bibliographie, Gauthier-Villars, Paris, 1889, Plate 5. Almost certainly from Kater's original paper: Henry Kater (1818) 'An account of experiments determining the length of the pendulum vibrating seconds in the latitude of London', Philos. Trans. Royal Society, Vol.108, p.33
Author: Henry Kater
Permission: Public domain - Kater died in 1835
Usage Terms: Public domain
License: Public domain
Attribution Required?: No

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